BS”D
Sick has become something positive in today’s slang? Loshon sagi nahor? Turning negative into positive is never such a terrible thing (but actually the Lubavitcher Rebbe suggested that the word beit refuah be used instead of beit cholim and in Lubavitch we don’t use “hacholeh”/”hacholanis” or anything similar when saying misheberach for those who need rachamei shamayim).
What bothers me far more is that a word which is one letter off from sick is used freely by frum people who have no idea what the source of that expression is. That word, used to describe something unpleasant or of low quality, is pure nivul peh and is no better than the word which begins with the 6th letter of the alphabet.
But Syriansefardi, don’t be obsessed about things you say that are just slang (especially in English) so long as you are not inadvertently using vulgar slang.