It’s hard to say for sure if she’s sick or not. Allergies usually don’t start that young.
My middle child used to get congested alot as an infant. It usually started as a cold with a stuffy/runny nose and then it would progress to a very severe congestion with very thick mucous. I could never get anything out of her nose with the nasal syringe because the mucous was so thick. Most docs dismissed my concerns but one day I took her to an on call doc and he said that it was most likely an Upper Respirtory Infection. He said that babies don’t have sinuses like adults, but they can get URI’s. He said it usually starts as a cold and then a secondary bacterial infection sets in. He told me that generally if a cold lasts more than 7-10 days or begins to get worse after a week that it’s safe to assume it’s a bacterial infection and to treat it with an antibiotic.
So we put Eliana on an antibiotic and within a few days the congestion was gone and she could breathe through her nose again. This (cold followed by URI) happened at least four times in her infancy. I asked her regular doctor why she keeps getting them and she said some kids are just prone to these URI’s and Sinus Infections and that if it continued we’d do a cat scan of her sinuses when she got older. Fortunately she only had two or three more in her toddler years so we haven’t done any testing and she seems to be outgrowing this tendency.