I had my third IPL treatment today. Spots got darker.

Coffee Grids post IPL treatment within the first week is normal.  In fact, those "grinds" were superficial hyperpigmentation that has risen to the surface and will heal over the next couple days and flake off.  Continue using sunscreen at least a 30 SPF. You should consider adding a hydroquinone, retinA, and vitamin C to your daily regimen to maximize your IPL treatment results. The wonderful part about having an IPL treatment is that you can start wearing make up the very same day and it will not affect your laser treatment.

Hello,
It is important to consult with your physician but a "coffee grind" appearance after IPL is typically indicative of a therapeutic treatment.  

The IPL treatment uses selective photothermolysis because the hand
piece can be placed on your body to target different chromophores in
your skin. This process allows the wavelengths of light to clear tiny
blood vessels and pigment spots by forcing the hemoglobin in the tiny
vessels and the melanin in the pigmented age spot to absorb the laser or
light energy and heat and damage the spots without damaging the skin.
Dark spots become damaged (desquamate) and scab and fall off in 3 to 7
days. The tiny vessels in the treated area become pale and then the skin
returns to normal appearance in 10-14 days.

Other side effects post laser include sunburn sensation, mild redness and swelling.  Ice or hydrocortisone post treatment can help minimize swelling.  A daily zinc based sunscreen SPF >30  and sun avoidance is extremely important for at least two weeks after the treatment.  Make is fine- avoid harsh products like Retin-A, glycolic acid or salicylic acid.  
Good Luck!

It is normal for dark spots to get darker after IPL. The pigment / dark colors will then flake off like coffee grinds and leave a lighter more even complexion.