Because old war vets of 60 (thanks a lot since I'm 62) don't walk around injecting folks with IV syringes full of "HIV" except in the minds of folks who need therapy to get over this obsession that someone is sneaking around poking them with needles in the middle of the night.
Seek psychiatric help and rent a better place that doesn't have either bed bugs or drug users.
Since the pregnancy tests were negative, it is doubtful you are pregnant unless of course, you tested too early before implantation took place (however, if implantation has not taken place, they any feeling of sickness would not be due to pregnancy).
And ironic statement considering the source stating this.
There may be more need for foreplay. And the OP needs to consider that not all "fooling around" needs to end up in an actual act of sex. Often when a couple is having difficulty with some area of intimacy a therapist will suggest that the focus be on the foreplay with the specific suggestion NOT to actually end up having intercourse.