Ah yan talaga ang sign na mainit sya internally, bes! Cold extremities with a sweaty head is pretty common sa babies, pero since five months pa lang sya at minsan medyo mainit ang feeling, I'd really suggest checking with your pedia just to be sure, baka may slight fever or hindi lang sya comfortable sa room temperature, kasi a few of us moms realized our babies were overdressed or ang aircon was too strong na. Keep monitoring kung paano sya generally, alert, feeding well, normal bowel movements, pero better safe than sorry with the little ones talaga!