I h old lab pupjust got a 3 month lab pup need help?

i brought him to vet 3 days ago they said he had a urinary tract iinfecton.he had a blockage. they gave him shot of pain reliever and antibotic.we also been giving him both twice daily since ,plenty of water,exersize. he got more perky. started to eat. peed better. 2nite we noticed he was peeing more blood, having that trouble peeing after going. and wining. im very concerned,is this normal or part of what they go through during the treatment.i give him plenty water. he runs around. but now hes just wining and keeps trying to pee every 5 min.help not sure what to do, never had this w/ dog before