Allergen Free BF Menu?

My EBF LO is 5 weeks and we have been dealing with stomach issues for the last 2.5 weeks.  At first I thought it was oversupply but now think it is an allergy because he had a few days of blood in his stool.  I went DF 1 week ago and it has stopped the bloody stools.  He still has mucousy green poop and the last few days is having reflux type symptoms.  He is spitting up frequently and in pain (crying when spitting up, spit up has a bad smell, gagging, waking from sleep crying, drooling).  We have an appointment next week with a pediatric GI doctor.  

Before the appointment I want to try giving up all allergens/irritants to see if that helps. Does anyone have suggestions for an allergen/irritant free menu?  I am OK just eating a few of the same foods every meal. I am also a vegetarian which makes it super hard but I will do whatever it takes.  I just want some ideas for simple healthy meals, I feel really overwhelmed when I look at the allergen/ irritant list.