Baby unwell advice

Tw possibly baby illness⚠️choking Hey I wanted some advice,my boy is nearly 4 months he had Covid at a month or 2 old and since then haven’t been right he is sneezing a lot he is trying to cough stuff up but ends up chocking he sound so congested and abit of crackling when he breaths sometimes he also does a lot of spit bubbles and is sometimes going 5-6 hours during the day without a bottle, he also does quite deep breathing sometimes and I keep saying all this stuff about RSV so I keep worrying . I have been doctors they keep telling me he is fine but I just feel like he isn’t. He is still smiling and happy but I don’t know I suffer with health anxiety too so not great I over think everything😔