Some allergy remedies are stimulants, but some are quite sedating and are often misused as sleeping aids. It's the stimulating ones that might contribute to anxiety. But there are many natural antihistamines as well if you're just trying to unstuff your nose that are neither stimulating nor sedating. So there's one avenue of alternatives for you. You're also saying that a stuffed nose or congested breathing is causing your anxiety attacks. They may be causing something, but if you're in fact getting anxiety attacks they are caused by something else physiologically or by the way you think. Assuming your doctors have ruled out physiological causes such as thyroid etc. then the answer is to learn to stop expecting anxiety attacks. Not easy, but an anxiety therapist might help you, and if it gets so bad you can't function medication might be necessary. But first you need to decouple the anxiety from you other health concerns in your mind.
Anxiety often manifests itself in breathing. You've probably learned how to slow your breathing to calm yourself. If you find times when that doesn't work, can you focus on something else? Do you play music? Do you have favorite music to listen to? Does it make a difference if you're seated or laying down? Does a walk outside allow you to calm down? Try some of those and focus on what works best for you. Knowing that playing xbox helps you is good, but you may get anxious one day while doing that and you want a few other ways to calm yourself. Best wishes.
and also i have well controlled asthma but the doctor said that anxiety medication can trigger asthma attacks so i dont know what to do and i and i feel really down sometimes though my day but when i am on xbox with my friends playing a game i can have fun because i ignore everything around me .