Suggest Treatment For Crabs With Severe Itching

I slept with someone two days ago who had recently shaved and theyre pubic area smelt very strongly of chemicals. I then woke up at 4.30 am with mild itching in my groin area, and today pulled a bug off my leg which im worried might be a crab.

The person denies having had crabs, but I think he's lying. He'd obviously been treated, hence the chemical smell, but how can I have it, is it possible some had survived or he hadn't killed them all?