why has my baby started screaming as soon as he wakes

[stdorothymantooth]

I have a 11 week old ds with colic, this seems to be getting better we can settle him easier, however, he has started screaming, as soon as he wakes, literally as soon as his eyes open he starts screaming
Spoke to gp yesterday who said that combined with the colic it could be a sign of an allergy so has given us a prescription for pregestemil. I'm a little scared of assaulting the poor mites digestive system with too much so am looking for opinions/experience, has anyone else's baby done this?

And does anyone know anything about pregestimil x

Often babies do this because they've finished one sleep cycle and want to stay asleep for another one, but can't - and are yelling for help.

DS did this for months & months - if i bf him (sometimes if I rocked him), he'd go back to sleep and wake up cheerful.