Extremly congested baby Dr office close?

My son is 5 months old he started to run a fever of 101.5 last night, I gave him tylenol and the fever went down but he is really congested. The congestion got so bad last night that is was really hard for him to breath. Well I call the Dr office today and they are close, they don't have a nurse on call. All this started at 5am it is now 3pm and he still has a fever which I have been giving tylenol for. What can I do for the congestion? Of course if the congestion gets has bad as it did last night I'm not going to second guess myself I will be taken him to the E.R like I think I should have done last night. I'm rally worry about his breathing it is not that bad right now What can you recommend? Do you think I should take him to the E.R right now? Anything else that I did not ask that you would like to mention?