Ay, nakakasakit yan! At 6 months, maraming things pwedeng maging culprit, teething na, developmental leap, or baka sleep regression na naman. One of my mum friends nag-share na sa age na yan, ang babies ay mas aware na sa surroundings kaya mas mahirap mag-settle, lalo na kung may ingay or activity around. Siguro try mo rin kung saan siya nap, some babies are fussy about the nap spot talaga, cold, mainit, o uncomfortable sa damit. Since papalaki na, check with your doctor din kung may other signs na something's off, pero most likely normal lang ito sa stage niya.