My 3 month old expressed breast milk fed baby sometimes spits up clear liquid. is this normal or should i take him to a dr?

Stomach juices: Sounds like normal baby spit-up. If he is growing and gaining weight well, a happy and content baby and not having any respiratory problems such as cough or wheezing that could be caused by reflux, i wouldn't worry about it.

If this only: happening occasionally and is a small amount,it may be normal.Has he been growing and gaining weight?Is the spit up ever projectile vomiting?Does he seem unhappy when he spits up,or is he what we call a "happy spitter?"If he isn't gaining/growing,has projectile vomiting or is crying when he spits up,please take him to his doctor.Otherwise you can have him checked at his next visit (at 4 months).