Post any trauma especially in children, presence of any ENT bleed (Ear, Nose, Throat/bleed from mouth), change in sensorium (baseline activity), any vomiting, any paroxysmal episodes or altered behaviour is an indication for observation at hospital requiring further work up and management. There could be a co-exist viral illness which makes the situation tricky to say the crankiness is because of post the fall or illness. To conclude, probable could be post fall since viral illness 1-3 days following illness they improve.

Is baby playing? Please consult once with your pediatrician for evaluation and examination of head

Fever is not related to the fall. Please visit a pediatrician for a physical check  treatment as he is crying all the time and not eating

Visit physically once for evaluation

Both are different conditions and not related. Treatment required for recent problems.

Get physical consultation done once