This is the 3rd day my 8 month old with a fever. Really runny and blocked nose and potentially teething.?

Pls c your Doctor. if you can, 3 days of fever, I am not sure was it high or low grade, and whether your child is feeding well, with no other symtom, such as diarrhoea or vomiting, teething would cause some fever and excessive salivation, but not for long, also your baby might have an upper respiratory tract infection, most probably of viral origin, but better off be checked, goodluck.