Gravel inside mouth

I have 1 cichlid that is about 3 inches and has very small gravel in his
mouth!!!

Why?

I have removed 1 piece, it was much smaller than his mouth and loose inside,
so

he could have easily spat it out himself.

The bottom of his throat is drooping/bulging slighly as if his mouth is
stuffed

with food, however when I looked inside his mouth his throat appeared to
have

enough room to eat and swallow.

His mouth is too small to look deep inside so I cannot clearly see how many
more

stones there are, when I removed the first I could not see any others until
he

was back in the water; so they maybe fell to the back of his throat. His
gills

are reddened and he appears to breath faster than the other fish but this
does

not appear to hinder him. His stomack is never full looking but neither is
it

shrunken/distended

He has been like this for about 2 months, I never noticed a bulging throat
the

1st month that I had him.

I think that the fish is a hybrid with a Labidochromis caeruleus, looks
similar

but is missing the black stripe on its dorsal fin and the colour is dark
yellow.

The fish was bought on its own and the shop said it was locally bred.

TIA
Dave S