What Causes Molliscum Infection On Skin?

my son has molliscum and was diagnosed about 3 months ago, I was told that it would go away on its own, which could take up to 6 months.. He still has it and today my cousin took him in for a second opinion. she was told that it could be burned off and could treat it with cream, I got a referral to dermatology. but my cousin was readying up on it here online and she mention something about HIV and asked the doctor today about it. The doctor said that we could have him tested for HIV but we would know if it had to do with his immune system shutting down that would make him more susceptible, that there would be a dramatic change in health, loss of weight, always sick, etc. How can someone contact molliscum? What is your opinion on this?