@ddljohn-- I get sinus issues whenever my allergies act up too. I usually use over the counter allergy medication. I've used loratadine and diphenhydramine (both generic names) in the past and both work pretty well for allergies. Usually if I can get rid of my allergies, my sinuses get better in a few days.
If I'm really stuffed up, then I use decongestants and/or nasal sprays and those are available over the counter as well. And you can always do basic nose washing at home with some warm salt water. Inhale some salt water into your nostrils and then release.
Or you can get a netty pot at the pharmacy. It's the same idea, you pour warm water through one end of the pot into one nostril and it comes out of the other nostril. It helps get rid of excess mucus and you'll get a good night's sleep.