worsen
decline
degenerate
deteriorate
devolve
drop
exasperating
exacerbating
aggravating
wusser
aggravate
exasperate
exacerbate
deteriorating
fall away
suffer
deterioratingly
tant pis
go from bad to worse
disimprove
go to shit
freefall
take a turn for the worse
downhill
deteriorationism
submediocre
confound
poison
wretchful
miserably
agudization
weakening
degeneration
worstest
deterioration
suboptimal
made of fail
below average
shank
pejoration
misreform
cod
dog shit
go to pieces
double-plus-ungood
prill
chronic
deteriorationist
downslide
stinking