"He also has other psychological symptoms like the following :
distrust in people, fear of abandonment, borderline personality disorder, paranoia, suspicious, delusional/unreasonable thoughts, poor memory, post-traumatic stress disorder, always snooping around in my phone/computer thinking I am cheating on him, etc."
Something is very wrong here.....Borderline Personality Disorder and PTSD are not symptoms. They are serious diagnoses.
The mere fact that you mentioned these two things indicates that he has heard these things mentioned before and was possibly diagnosed by someone.
That coupled with your statement that his negative thoughts "increased" indicates that these "symptoms" have been ongoing and now the situation is exacerbated.
Co-morbid disorders, paranoia, "snooping around in my computer/thinking I am cheating on him" ? And constant scratching when stressed with scabs falling off? Scabies (with a question mark) means you do not KNOW if the sores are scabies? Why not get them checked?
I'm sorry to say this but the first thing I would wonder is whether this person is taking any psychostimulants (Adderall, Ritalin, Focalin, etc). I assume that he is not doing street drugs (I don't know why) but barring that, these sound like side effects of amphetamine use. Either that or an underlying psychological issue or both.
Sorry but I do not believe that parasites
cause all maladies of the mind and body.