Cough and congestion since 20 days

Hello all,

My 2.5 yrs old boy is having cough and congestion since 21 days. Still no sign of full recovery. In between it healed for 2 days but again resurfaced. His screaming and crying make the cough worse. We tried three different cough syrup but haven't been getting satisfactory results.

Ps- he just started day care and went to day care for week and got this horrible cough.

What else can be done?

Anyone else whose kid experienced never ending cough?

Both of us parents are just tired taking care since 3 weeks but he is still not getting better.