Treatment For Baby's Low Appetite, Red Spots, Frequent Cold?

Question: My baby is 3 months old now. When he was 4 days old he was diagnosed with jaundice and qas on phototherapy for two days. During his nicu period he caught some infections resulting into the diarrhoea which lasted for a month. He was also diagnosed with lactose intolerance during that period due to which I had to stop BF and given zerolac. After 5 days I again started feeding but the milk supply was low so I had to suppliment him with zerolac. Due to my medical conditions my milk got reduced.so he was totally on formula.When he was 2 month old my dr. Advised to change the formula and and switched to simyl mct and again his test reducing sugar results says present*. At the age of 2.5 his test revealed reducing sugar absent. So on advised of dr. I strtd giving farex1 and gradually increased it. My baby strtd to spit and remain gassy through out the day. I gave him colicaid, colimex, vitazeme drops but nothing worked. Previously he used to take 90 ml to 120 ml at a time now he only takes 30 ml to 60 ml and feeds every 2 to 3 hour. Sometimes refuses to feed and cry. He shows red spots sometimes. Whether is very cool here, he frequently catches cold. I am trying to relactating again its working but about 20 ml milk comes out. He crys after breast feeding also. Plz advice.

Will long term feeds of zerolac be safe? My psed said it may not provide appropriate nutrition. And simyl has added his weight, as he was born lbw 2.2 kg.What bout nan pro formula? I have stopped giving him farex1 now only simyl and bf. He ie bit relaxed. Forgot to mention he is on bottle feed.