Massive hugs. Yes the bum soreness is awful. Try a bath with some bicarb & some nappy cream around the external if that helps.

Activated charcoal caps will help with runny poos, absorb any toxins in your bowel, and relieve the gas.

In the meantime I have a regimen I adopt whenever my bowels get out of whack, it might be worth trying:
1. Probiotic: you need a product that says rhamnosus (that's the gastro-buster) AND boullardii (that's the healer).
2. Bovine colostrum. I use a capsule product called Travellan - it has some kind of magic antibodies or something, it works to prevent gastro when you're travelling, it's magic stuff.
3. A very gentle fibre-product. I use the fibresure stuff which dissolves into food & drink. It's made out of chicory root, it's a pre-biotic, and adding that little bit more gentle fibre will help slow everything down. I would steer clear of bran & psyllium for now as they can irritate when you're not well.

If it goes on too much longer, you might need to see a dr to get it checked out.