Answers for ur questions
1) yes thing is real infected needle have potential to transmit some infectious diseases
HIV is one of them ..but these days syringe and needles are very cheap of cost and no one are using the same infected syringe
2) no medication can affect the hiv screening test
3) regarding to your history there is no need to repeat the test and after 28days hiv duo test is 95% accurate and regarding ur exposure it's very highly unlikely to get infected by blood drawn for a lab test ...don't get panicked
Next Steps
even still it makes u restlessness.. repeat test after 30days...it will be negative..relax
Health Tips
if you want to know further details about the exposure and
hiv transmission contact me on practo