So the first sex contact was about a month ago - where you using a condom on that occasion?
If yes, I think you have had a reaction to the condom itself. It is most likely contact dermatitis or an allergic response - fundamentally it is most likely a skin issue.
It could be the brand of condom you were using was not of the highest quality - the most famous condom brands have a great deal of testing and research and development regimes, where other brands may not do so.
Try switching, at least to a different brand, or try a non-latex type for your next sexual encounters.
The distressed skin you have now will take its own time to repair itself and fully heal, this could take weeks or potentially even months.
Try not to expose your skin to anything like skin cream / lotion, baby oil, any form of lube you may use for masturbation, even severely limit the exposure to soap and shower gel and other forms of body wash - particularly if you shower regularly. Simply wash your penis with water, and you must ensure you fully dry all the skin of your penis so that you do not cause any further damage to the distressed skin