How long has this been going on? Also do you have a fever?
If you think you may have had a fever it's possible it could be strep, but without a culture is a test. But from your symptoms it does sound as though you do have a sinus infection, which can cause all the symptoms you have. Start taking a decongestant, use a humidifier, sitting in the bathroom with the hot water running from the shower can help. Gargle with warm salt water too. If there is no change in the next couple of days, then do see your doctor, as if this is strep you may need a course of antibiotics to help clear this up.
So with the symptoms and your age, I wouldn't think anything serious at this point.
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When pressure builds up in the sinuses due to an infection or inflammation, swelling (inflammation) pain etc., can occur within the mouth as well. But do keep an eye on the area as well, since you are sick this can cause your immune system to be down, which then could cause thrush to occur in the mouth as well. So if it starts feeling really raw and sore, watch out for enlarged taste buds, a white coating etc.
Hope this helps.
When you gargle with the warm salt water, swirl it around your mouth. Also eating yogurt and swirling it around your mouth as well.
But with all that said, it may be the opposite of what is going on. You may have an infected tooth, which then is causing the other symptoms, due to infection and inflammation and the infection may have gotten into the sinus cavity. Try the above for the next day, if there is no improvement, I would be seen by your doctor which then can confirm if this is a dental issue or vice versa.