Tattoo removal side effects, all the black ink turned brown will this go away or can it be treated? (Photos)

The brown color of your tattoo is caused by oxidation of the iron oxide black ink used for your tattoo. Oxidized ink will continue to go away with continued treatments.
Your altered skin pigment should return to normal after your treatments are completed, although it may take a good many months.

The brown will probably continue to fade with time and further treatments, but it is unfortunate that something that is advertised as the latest, greatest machine (Pico) is taking so long to remove your tattoo.  I am personally more a fan of a traditional Q-switched laser for removals.  Usually black/dark blue ink is the easiest to remove and doesn't take that many sessions, but it all depends on how new your tattoo was when you started treatments and whether or not it was done professionally.  I would consider getting a second opinion at this point after investing so much time and money, but it is likely the tattoo will eventually be gone.  Best of luck!