My son is two months n ten days old his weight is 5.4 kg is it ok n he has block nose n cough some time throw milk also?

Too much mucous: Babies breath through their noses and get a lot of mucous in their noses which can block the passages. Use a bulb syringe to suck out the mucous before feeding you can then use saline nose drops to keep the nasal passages clean. His weight seem to be fine.

Depends...: If your son was born at 3 kg, he is growing well. If he was born at 5kg, he is not growing well. Spitting up milk is normal. Some babies do it a lot. If it causes him pain or he spits up enough to interfere with growth, see your doctor. Put a few drops of saline in his nose and suck it out with some sort of aspirator to help with the congestion.