Theres a lot of advice about diet on this forum but you have to have a lot of patience to find the one that suits you best and what you can tolerate.

To get enough nutrition and to gain weight I used a complete liquid food called Absorb + which has all the nutrients you need as well as extra l-glutamine to heal the bowel and reduce diarrhea, and it's specifically formulated by a former colitis sufferer to be tolerable and easily absorbable.
Vegetable juice is good but not alone if you're weak and low weight, you need to gain strength first but you don't seem that low weight. You still need the nutrition though

You need to give your digestive system a rest while increasing strength and I believe that the absorb+ or something similar works fastest.

If you can't get that then you could get some hydrolysed whey (preferably isolate) protein and l-glutamine from a
bodybuilding supplier and all the other ingredients

If you are anaemic you will need to take a good iron supplement, I found iron biscglycinate worked best for me
You can also eat what is tolerable at the same time but if your colitis is very bad and you have a lot of blood loss it may be better to use the liquid diet for a while till it heals somewhat.

You also must rest as much as you need to and get plenty of sleep, avoid all stress as much as possible and try to stay relaxed.

I went through what you are and I thought it would never end but it did and it would have done quicker if I'd not tried to carry on as normal and looked after myself better.
You can't fight it, you just have to learn to let go and give your body what it needs to recover and then just wait 'till it does

There are several methods that can be used to deal with dysbiosis and they've all been mentioned here.
I would be wary of Miracle-Mineral-Supplement because although some including myself benefitted from it others have not and overdoing it is a possible reason, or wiping out too much good bacteria.
Also tolerance to it varies.
Monolaurin also looks useful for this purpose as does potassium Iodide or lugols(reduced with vitamin c)in the right amounts

Zappers have proven useful as have vitamin e enemas
Coconut oil and fish oil are antiinflammatory as are many herbs. Coconut oil and some herbs can also be used as retention enemas to heal the colon

So you can see theres plenty you can do and I'm sure I've left something out

Drugs I feel are always a bad idea and they never worked for me either