Blister on my lips. It as hsv or fde!

I m 26 yrs old male have recently started noticing blister on lips and soon after 2days on my genital area I consulted doctors on practo, they said its a cold sore nd gave me medication for that It took 10 to14 days to completely recover. But next month it again arrived after i got a cut on my lips with tongue cleaner I got a consultation again they recommended the same medicine acyclovir400 3times a day for 15 to 20 days Now after one month Again it had come same blister Its symptoms include numbness in lips area...and lips become dry and chappy and they become sticky and then blisters form in same area... A friend said it could be Fixed Drug Eruption...since every time my lips are cured they are becoming darker too much pigmentation and they are not becoming normal Genital area also becomes a bit dark This is the 3rdtime a blister has formed And I dont know what might be the reason I got checked for hsv but tests are negative 2times I needproper help to diagnose it as hsv or FDE