Fever!

Lu

So my LO is 8 months and has a couch not in his chest just a cough and a nose that is just dripping. He doesn't seem to want any solids which I know is okay, and he is drink breatmilk just fine as of now. He has a fever of 100.6 rectal. I gave him Tylenol to help with discomfort as it is bed time. But he also has two teeth coming through poor guy. My question is how long should I wait till I call doctor? What if fever stays or get worse? Thanks all!