My friend keeps getting me sick

I have this friend that has now given me this horrible whooping cough twice in one month. The first time was from sharing a drink with her, I developed what felt like covid for about 2 weeks this passed and I felt much better so we agreed to go out again, we went to a gig and water was sparse so I ended up sharing a drink with her again out of fear of overheating and now I once again have a horrible whooping cough. The whole time she’s not been outwardly sick but she’s the only person I’ve shared a drink with. She’s a very strong vape smoker so I don’t know if that has anything to do with it. I’m definitely not going to share anything else with her because it’s just a bit too weird to me that this has now happened twice with the same person.

Does anyone have any remedies for a chesty cough as I’ve not been able to sleep and my parents are beyond angry at me for coughing when I can’t help it. I’ve tried medicine and my doctor won’t give much for a cough.