I am a sinner and I have repented and sought Allah for forgiveness, but am still feeling bad for myself and not feeling comfortable. What should I do?

If you have sincerely asked Allah for forgiveness, really mean not to do it again, and have done your best to repair what was done wrong (like given back stolen property, apologized to someone you hurt, replaced something broken) there is no reason to feel uncomfortable. Allah is pleased with those who repent! Even if you slip up and commit the same sin again, just repent to Him again and try not to go wrong again, for as long as it takes to get it right. Shaytaan may be making you uncomfortable: say the 3 quls morning and evening, and ayatul kursi or surah naas when you feel bad, and keep in wudhu and ask Allah for protection. Otherwise good job! You're on the right path!