i have had that same pain.
it was from my flare.
i used to cry and still do when its that bad.
i even vomit when im on the toilet due to the pain being so excrutiating.
i cant say if it is from anything else in your case, but with mine it was all from the UC.
and the pain was in the same exact spot as well as all over the place.
right side, left side, rectum area, above colon, behind colon... you name it, it hurt.
steph - 32 - female - gold coast australia - UC since 2000
severe UC in descending colon and sigmoid colon ONLY
mesalazine granules 3g x1 a day (much nicer than a million tablets a day)
prednisolone 25mg x1 a day (ick ick and did i say ick?)
enteric coated fish oil -omega 3 (so they get all the way to my colon)
vitamin D3 x1 a day
tumeric capsules - if i remember to take the bloody things.
i still eat what i want, when i want, if i feel like eating at all :(