What Causes Sugar Levels To Dip After Food Intake?

I am a 45 year old male. I have been diagnosed with type 2. I have been having many checkups by cardio´s, endocrinologists, Gi doctors etc. I initially started to experience fast heart rate and weakensss a few weeks ago hence the reason for all checkups. I was diagnosed with type 2 about 18 months ago and take Metformin. I have given up alcohol completely as of 6 weeks ago and am on a strict diet to lose weight. I weigh around 245 pounds and have lost around 15 pounds. I walk quite a bit everyday in short stints. I have noticed that I struggle to get my glocose level up and start to feel somewhat odd. Non specific symptoms whicxh if left alone then develop where I have to have fruit and or something sugary. This particularly happens after lunch and now even in the evenings. After meals I expect by sugar to go up and last and maintain at least 3 hours but often it goes down within 1 or 2 and below what it was. Not sure ifthis is reactive hypoglycemia. My sugar can spike to near 200 at times as well but very rarely. Quite worried now. Just had a big dinner and started to feel heart race and was surpriced. Measured my sugar and it was 90. Took 2 glucose tabs and a sip of orance juice to lift it. I have to say that sometimes I have symtoms when my sugar is between 90 and 100 and sometimes only when it reaches say 80 or 75 which is much lower. It is really frustrating me me as to what´s going on. Really dont like the thought of a tumor but maybe I should get this checked out