hypoglycaemia confusion

HI, I've not actually been diagnosed as diabetic but I have PCOS possible caused by hyperinsulinism. My GP has just put me on metformin despite not being overweight. This was prompted after I bought a blood glucose meter the other week and seem to be getting strange results.

My fasting glucose on waking is normally about 5.8. This falls throughout the day no matter what I eat and is normally below 4 by 6 or 7pm y which time I am really lacking energy. Oddly the MORE carbs I eat the more it FALLS?!? Has anyone experienced this?

Today it was a bit different though. Last night I ate a lot more carbs than usual - was having a 'hungry day', yet at 8am I was at 4.2 (the last 10 days the lowest morning reading has been 5.6). By 12.30 I was 3.9, at 6pm 3.3 and not feeling very well. I do a lot of sport and still wanted to do something tonight so decided to get a flapjack on the way home and ate half of it. I was meant to do a proper training session but decided to appease my mental unease by just doing a jog for 35 mins. I struggled like hell with no energy but when I came back my glucose was now 5.0. Is it possible for half a flapjack (150cal) to do that??? Plus I did exercise. If I take readings before and after exercise I am always the same or higher after exercising (am doing between an hour and 2 hours of training at a time). I would have thought this would lower my sugar??

I'm finding managing this hard because if my sugar drops low eating carbs actually makes me feel more unwell and doesn't necessarily raise my levels.

Thanks in advance if anyone can enlighten me

Thanks to both of you. The metformin is because I have gained a lot of weight unexplained and can't lose it despite practically starving myself (which is resulting in severe depression). I think you are correct that I need to see a specialist though. I'm fed up of feeling dizzy and tired most of the time and not being able to do things I want to (and also feeling like a fat whale).