Daycare Woes

Kate • Mama to the cutest baby boy.
I went back to work on Jan 4th after a 5 month maternity leave. My son is very happy at his "school" and they love him there. He is very well taken care of. 
But he has been sick since the moment he started. Everyone says this is what happens when babies start daycare and thathe's building up his immunity but I just can't anymore. We are on day 48 of him being miserably conjested and a wicked cough that won't go away. He has already had 2 ear infections, 3 bouts of conjunctivitis and missed 2 full weeks (1 each month) due to fevers. This past week was horrible with flu like symptoms. Poor baby was in so much pain. 
Before all this he was pretty much sleep trained and on a great schedule. He has now been sleeping jn our room, either in the Rock 'n Play or in bed with me when he's really bad because he can't lie flat. All the conjesting and coughing keeps him up crying all night. 
We are exhausted and also keep getting sick ourselves, just passing it around. The doctors keep saying it's normal and some babies just have bad first winters, especially if they are in daycare. 
We are spent. Not sure what else to do...