S.W.
It could be a lot of things - stress, diet, acid reflux, hormonal changes...
I was on the pill for a total of over 20 years, and did not have any negative side effects. And then just this year started having those symptoms you describe - heart burn/acid reflux, gas & constipation & bloating, anxiety and sleeplessness. I thought it was all peri-menopausal symptoms (I'm 51).
My doctor tested me for ovarian cancer (negative!) and also suggested I go off the pill just based on my age. I did. ALL those symptoms went away almost immediately. I can now eat & drink all the things that caused my stomach pain, I'm sleeping better, and I have NO hot flashes, anxiety, moods or anything. And perfectly regular periods, too...