Hi Jo and welcome.
Firstly there is no need to panic. Your HbA1c reading at 50 is only just over the threshold for diabetes, which is 48, so it would be unusual for you to have symptoms at that level ..... other than perhaps sugar withdrawal symptoms if you have previous been consuming a lot of sweet stuff and have suddenly cut back. My reading was 112 when it caused me symptoms .... which were unquenchable thirst and consequent weeing but otherwise I didn't actually feel all that bad and there are some members whose readings were higher still, so your 50 is really nothing to worry about.
I am actually quite surprised that they have given you Metformin with such a low reading rather than seeing if you can push it into remission with some dietary changes. Those need to involve reducing your consumption of carbohydrates....fruit, chocolate and toast were not great choices to eat.
I agree with
@Martin9 that you may have had a residue of something sweet on your fingers which influenced the first readings of you may have been suffering the effects of dawn phenomenon, which is where your liver releases glucose into the blood stream to give you the energy to get up and "catch" breakfast.... a cast back to our caveman days when we didn't have a fridge to store our breakfast and had to head out on foot to hunt it down and needed a surge of glucose to fuel that.
If your wobble moment was after taking the Metformin it may have upset your stomach, especially if you just took it on an empty stomach or with a bit of fruit.... it is renowned for causing digestive upset and is best taken with a substantial amount of food,
mid meal.... it might be best if you take it with your evening meal instead of in the morning since you are taking it just once a day at the moment.
It is also important that you are quite structured about using the BG meter. Before food and 2 hours after food is the recommended schedule and you are looking for a rise of no more than 3 mmol between the readings. It is important to keep a record/diary of what you ate and your readings so that you can see the effect that food had on your levels and therefore adjust the portion size or carbohydrate content to keep your readings more in range. You will usually see patterns over a couple of weeks so don't get too fixated on any one reading. You are looking more for trends.
There is almost no risk that the Metformin will take your BG too low and even if it does, it will not go dangerously low like injecting insulin can do... it just doesn't work like that, so don't guzzle high carb stuff if you feel a bit wobbly. By all means check your BG if you feel unwell but it would have to be below 3.5 for it to need treating with a few jelly babies or glucose. Otherwise have a few nuts or a chunk of cheese as these are low carb options which will satisfy you without spiking your BG.
Carbohydrate rich foods are the obvious sweet stuff, like sugar, sweets, chocolate, cakes and biscuits but also fruit and in particular fruit juice but more importantly bread, cous cous, pasta, potatoes, rice and breakfast cereals. These are the things you need to cut down on to push your diabetes into remission.
The good news is that meat, fish eggs, full fat dairy (avoid low fat yoghurts and go for creamy natural yoghurt) cheese butter cream etc are all on the menu with lots of fresh leafy green veg, most of which benefit from being cooked in a knob of butter or a dollop of cream cheese. Mushrooms are great and Mediterranean veg like courgettes, aubergines, peppers tomatoes and cucumbers I make a big pan of ratatouille to last me a week and have it with chicken or burgers or sausages. Cauliflower makes a great carb substitute and can me mashed with mustard and butter or cream cheese instead of potato mash and served with bangers or used to top a cottage pie, or it can be finely chopped as a rice of cous cous alternative. Courgettes spiralized to replace spaghetti etc. We have lots of imaginative cooks and bakers here on the forum who have found low carb alternatives to many recipes.
Anyway, I hope I have been able to put your mind at rest a bit. Do wash your hands before testing and make sure to take your Metformin in the middle of a substantial meal ... the time of day is not really relevant but protecting your digestive tract against upset is important.... My gut feeling is that this is probably what caused your wobble this morning. Many of us use apps to log our foods and BG readings and calculate carbs and even calories although I have found that cutting out the carbs means I don't have to worry about calories, and even keep tract of physical activity.
Good luck and keep us posted on your progress and feel free to ask whatever questions come to mind. Some one here will almost always know the answer.