Why did the black ink turn blotchy and look blown out after my first laser treatment? (Photos)

Hello M.  Your tattoo looks exactly like it should look after starting tattoo removal.  The ink does not necessarily get universally lighter in all areas at the same time.  The goal is slow and steady fading throughout the tattoo over time.  Not to worry, things look good.

tattoo ink takes numerous treatments to improve and can fade unevenly.  I suggest you see an expert and do it with a PFD patch.  Best, Dr. Emer.

Your tattoo will start to fade slowly as your body is absorbing the ink that has been broken down by laser energy.   Will take several treatments, each time getting lighter and lighter. 
But do make sure your treating provider is using Q-switch laser. 

Thanks for posting your picture. Tattoo removal takes multiple treatments. 
Your tattoo looks reasonable in terms of one treatment. I would not expect a uniform fading of ink. It really is patchy which is normal 
Best wishes 

That is exactly what your tattoo should look like after your 1st laser tattoo removal session.  Laser tattoo removal works by breaking up the ink into much smaller molecules that your body can absorb.  The area's that appear "blotchy" are the area's the laser has destroyed the ink to a sufficient size that your body was able to reabsorb.  Your size tattoo will take up to 12 sessions to complete and it will fad less and less with each treatment due to the remaining ink being so small the laser has a harder time vaporizing it so don't give up.

Tattoo removal takes multiple sessions.  We recommend using the Picoway laser.  It uses thermal and vibrational energy to literally shatter the ink in the tattoo.  We recommend around 8 weeks between sessions.  What you have is totally normal and the ink does not go away uniformly and goes away gradually over time.  The laser breaks up the ink and then your body carries the ink away over time.  It takes several sessions and your laser looks totally normal at this point.  

The appearance you describe is normal for laser tattoo removal. Tattoos usually do not fade out, but vanish first in the areas where ink is most shallow. The deeper ink requires more treatments. Tattoos in the process of removal are not very pretty, but the plus side is that yours is going away nicely!
Keep going!