Stop feeding so frequently. LPS corals will eat every day if you would feed them. I've read a couple articles claiming that might not necessarily be good for them. The theory is (I guess it's actually happened a few times) feeding all that rich protein will produce lots of large and fluffy polyps for awhile - but they can overgrow their boney skeleton underneath. If this happens they can deflate and shrivel or die.
The LPS is a large polyp STONEY coral. It has the same skeletal structure underneath all those polyps as you would normally see exposed on an SPS coral. The stoney skeleton is not grown with protein. It's grown with trace elements and calcium. It takes significantly longer to grow than the fleshy polyps - especially if you're feeding the polyps a rich diet on a regular basis. But you can't have polyps without skeleton. The limiting factor is skeletal growth. Making polyps grow is easy - as you found out - just feed them. Only time and good water conditions will accelerate the stoney growth required to support the exposed polyps.
I'm just guessing though. It won't hurt to stop feeding them for a bit. I have some LPS that I never feed (favia and chalice) and they grow just fine - albeit slowly.
When in doubt - do some water changes. IMO that's your first line of defense when something is not looking normal in the tank. Changing water removes toxins, helps stabilize major parameters such as pH, alk, calcium and will help replenish trace elements.
