I am beginning to have troubles with my trumpet. One day it randomly started making a weird noise when I play it. It`s when I hit the notes around F, G, A that it makes some noise that sounds like there`s something stuck inside it, like a piece of paper.

I`ve cleaned it multiple times, and found nothing that could be causing the problem. Does anyone have any suggestions?

does it sound like the air is stopping for a few split seconds at a time or like a lot of air is coming through? what mouthpiece are u using and how long have you been playing?

Have you switched any kind of equipment lately? Mouthpieces, trumpets, etc? If you changed mouthpieces, you should probably take your new one back if you can, since that likely means your problem is that your chops don`t match well with the mouthpiece.
Otherwise, it`s almost definitely an ambesure (<-- spelling?) problem. For a few days I would recommend playing only flow studies, long tones, and pedal tones for shortened practice periods. Stay away from higher notes whatever you do; if you have to play in school or something try to avoid playing anywhere above the staff and take it down an octave if you need to.
I would heavily emphasize pedal tones until the problem is fixed.
My guess if it`s an ambesure problem is that your mouthpiece is too low on your top lip, or not centered. You could also be using too much pressure; make sure your pinky is out of the ring and when you pull the horn away from your face there shouldn`t be a white ring where the mouthpiece was.
Some other less probable possibilities are that your corners are not firm enough for that register (make sure your cheeks, chin, or top lip areas don`t balloon with air when you play), or your lips are simply overworked (in which case you should probably not practice more than 10 minutes per day, and stay below the E in the staff in those practices).

Hope that helps

Could be something loose on the trumpet? If you have a finger ring, and you have it out, tighten the little screw all the way down. Or if it`s not that, you may have a problem I once had, I stepped on my trumpet one time (long story....) and one of the supports broke. Everytime I played certain notes it would buzz, so check all pieces, but like Willy or whoever said...check the Embrochure and the mouthpiece

Check your water key (spit valve)
Try both of them, if you have two.

Thank you guys. It turned out to be a missing cork on the spit valve. I just taped that up for now and it works.