Day care 11 month old crying. Please help me

Hello lovelies, my son started day care. After 3 days he got stomach flu since then has been very sick. Apart from that he cries a lot when we drop him off. He Does not drink formula there, but they say he eats well. Every time I go pick him up he is sitting alone in play pen. He is constantly whining. Also I have noticed his activities have reduced at home. He is not wanting to play with me or just not his own self. Is this normal in the beginning?! Or is there something going wrong?! I am scared to death to drop him off. Please help me here