If his pediatrician
has mentioned that nothings wrong with the chest then probably this issue of nasal congestion
should settle with time.Also in addition to using nasal drops use small baby nasa aspiration pumps to clean his choked nose.
Sweating a lot in the palms and body may be associated to hypocalcemia
(less Calcium) or it could just be his skin type which make him sweat.Diabetes
seems to quite unlikely to appear so early.Weight not gaining needs to be attended to let his pediatrician assess him whether its related to feeding issues,hypocalcemia or hypothyroidism