Cold for three weeks, nasal chest congestion, dry cough nowc followed by mouth sores on top pallet. red bumps with large white sores?

Sinus infection?: The mouth sores on your palate sounds viral, but if you have been sick for 3 weeks you might have a bacterial infection requiring antibiotics. See a doctor, rest and drink plenty of fluids.

Viral infection: The mouth sores following a cold or other disaeases are normally caused by an opportunistic type infector or trigger. Sores on palate are probably a viral source like a herpes infection. Weakening from your illness can have other mouth sores like apthous ulcers(canker sores) or even yeast infections, especially if you have been taking antibiotics. Eat well, drink lots of fluids, and rest.