Sqad, do correct me if i'm wrong, but not sure hydrocortizone cream is a good thing to put on your lips as a) the skin on your lips is thin already and Hydrocortisone thins your skin and b) its not good to ingest the stuff which if you put it on your lips you will inevitably do!
Have you tried taking any antihstamine tablets? If it is an allergy, they should help bring the swelling down. YOu could also try wrapping ice cubes in a clean cloth/flannel, and holding them against your lips. It should help with the hot sensation, and may bring the swelling down too.