What Could Be The Reason Behind Excessive Bleeding And Stinging Sensation In Abdomen During Period?

Several months ago I had random sensations of stinging around my belly button. That has stop now but there are time when it feels like there is something very firm above my belly button. Just started noticing that bump but isn't alway firm and tender. Can't make out a shape but if you bush in my belly button it is tender. I also have experienced weight gain of almost 40 pounds this year. I eat well, no fatty foods, nothing fried, etc so it seems weird especially since I am 44 and never weighed this much. Not even when I gave birth 18 years ago. I have also experience menstrual cycles that are bad by my standards. For 25 years I was a very light bleeder maybe 3 days total. No back pain, cramping or any of the other normal symptoms. This past year has been bad, I have all the usual symptoms and have very heavy bleeding. Doc says it's normal and I had it good all these years. But this month I bleed for 13 days. The most I have ever bled was 7-8 days and the last couple of days were light. Day 8 came around, I was only spotting during the day but by 7pm I started bleeding a lot, with lots of clots. Then it would taper of after a day and then do it again. I have seen any blood for the last 8 hours so I think I am done. So that with the belly issue, weight gain, most of which is around my belly but I have never been fat so I don't know how I carry weight. I thought my weight was because I haven't been going to the gym. Too much work behind the computer but 40 pounds, seems like something is up. Am I needlessly worrying? Oh and I am a lot more tired than usually but again that could be from being behind a computer too much. Thoughts?