It would be very difficult to make any kind of diagnosis without an in person appointment and evaluation. If you are unhappy with your treating physician, a second opinion may prove helpful.

Need to keep in touch with gastroenterologists in your area. Listen to their advice. Email medical advice from outside sources is not a good idea.

Sangarlingham

Fluvoxamine can cause diarrhea and omeprazole may put you at risk for c diff

If colitis was found then mesalamine can be tried but if no colitis the symptoms may be from small bowel inflammation and may respond to same Rx

It appears that you have irritable bowel syndrome so the focus should be on getting treated properly for that. The pain and diarrhea should improve on the right treatments, but you need to insist to the GI doctor that he/she treat you to get the relief that you want. It's not easy to get IBS controlled sometimes so you and the GI doc need to be persistent.