when you feel ready to introduce something other than liquids into your diet, do it really slowly & gently, and in tiny amounts. also, only bring one new food into your day, so if it's going to upset you, you'll know exactly which food the culprit is.
i'd think of it as weaning a baby... start off with things which are more mushy than anything (i know that sounds gross but it's a good way to wean your tummy back onto real food)... things like soft mashed potato, soft scrambled eggs, very thin light bread with cream cheese on, yoghurts (no bits).. and take it from there. if you're ok on this kind of thing, then in a week or so introduce foods which need slightly more digesting such as shredded chicken, soft veggies (no hard bits or stalks).
completely avoid things like vegetable skins, fruit skins, nuts, popcorn, sweetcorn, pineapple, mushrooms - all these things don't get broken down in our systems and can cause us a lot of problems.