Red spots/growths on coral banded shrimp

I noticed it first yesterday and today they look a little worse although
it's very hard to see (even with my glasses on). The spots are only on
her antennae things and are irregular in size and placement. Some look
raised and one antennae (is that what they're called?) is shorter than
the others, half the length. She was fine the day before but hasn't
raced out for a feed since the first few days I had her back a month or
so ago. I put it down to the fact there is more food going into the tank
as I also got more fish the same day, and therefore there would be more
for her to scavenge while not being watched. I observed her this evening
having a bit of a grab for the coral beauty which is normal behaviour
and is very half hearted.

Now the other thing that happened today. First thing this morning I
found a dead crab in the tank that I never knew was there (live rock
hitchhiker). It was very small, maybe a cm across the body and it was
red. I really wish I'd seen this little cutie alive. I'm not 100% sure
this wasn't a shell and not the whole crab but I'm a bit icky when it
comes to dead things. (I asked hubby to take a look but he was busy
making his latest "great" batch of home brew). I know it didn't smell
and it's legs fell off if touched which is what made me wonder if it was
shell only.

Could these two things be related? Disease? Punchup?
Tank is 700 litres and live rock went in in October, first 2 fish in
November and next 3 fish, leather coral and shrimp in December. I did a
108 litre water change today (ran out of R/O water). Coral is looking
better than ever and all fish are in fine health. All the other living
things in the tank look fine. Ca is still reading very high at 600 but I
am sending a water sample to the petshop next week for testing. pH is
8.4 and SG is 1.0225/1.023. I was really slack and didn't retest the
Ammonia, Nitrites, Nitrates and Phosphates which were all 0 last week.

I've just been down and checked the tank in the dark and the shrimp is
out and about. I think I am more concerned that she is
In the dark is the only time I get to see a tube worm that is about 5cm
across but I don't do it too often as it scares the fish to have a small
torch light around.

I'm going away for 2 days but have someone coming to check on the
fishand more importantly that he equipment is all running. I may not get
to read your replies until I get back so don't think you are wasting
your "breath". Just out of interest, I put the fish food in medicine
containers, the sort that are long and labelled for each day of the
week, 7 compartments. One medicine container for each tank. The "real"
food is in tiny containers in the fridge, one for each day. That way
nothing can be overfed by kindly fishsitters. I usually feed the fish
twice a day but only allow fishsitters to feed them once a day.

Cheerio
miskairal