The baby is now 4.5 months old and has become fussy. He started having…

The baby is now 4.5 months old and has become fussy. He started having trouble sleeping, waking up every hour (may be regression in sleep). At 5 months old, he was not very energetic today. He ate little. His stool became more frequent. The pediatrician said that soon teeth will come out. But the teeth aren't visible. To which doctor should I go? My mother-in-law started getting hysterical, saying they may have blinded him, and I already convinced myself that he might develop rickets. In general, help, where to go ?