You should google death by colonoscopy... You can find an article that is very informative on the truth about colonoscopys including long term effects that are possible (which I suspect you might be experiencing).
If you had a colonoscopy which was perfect 8 mo. ago, I am doubtful that you have a real serious issue. Rather than seeing a gastro., I would see a colon rectal specialist. Sometimes when my hems are acting up,I also feel pressure! I can't imagine you needing another colonoscopy. I have had good experiences with colon rectal drs. for my hems. They may just take their little light and look inside...not very far, it is quick and painless. They can tell if you may have developed internal hems and they certainly can produce a feeling of pressure. They can tell quite a lot just by that simple exam. Should your doctor suggest a flex sig test, it is simple with little prep. Wish I could be more helpful....oh, as far as the heat in the area, I have that as well. BTW. I also see a gastro dr., but for hemorrhoids they even suggest a colon rectal specialist.