Motorcycle running bad after oil change

Hey guys! I have a '99 Honda Shadow VT125. Yesterday i've changed the oil and oil filter and started the bike up, let it idle for about 5 minutes, ran just fine. Today however about 15 hours later the bike could not start and when it did only one cylinder was firing. After about 10 minutes of running on only one cylinder the second one joined in and i went to work. On the way there (7 km trip) it was underpowered, stalled twice at lights and (i think) it was misfiring, exhaust was popping when slowing down.

Does anyone know what could be the problem? The battery should be fine, gas tank is almost full, didnt mess with the carburator at all.

Thank you in advance!