If all antibiotics were rendered as useless why can’t we just switch to sulfanmides.... I’ve read that it may have terrible side effects but couldn’t it be an Alternative 

Could you be more specific? Sulfanmides appears to be a typo, so can I assume you are talking about sulfonamides? If so, sulfonamides are some of the oldest antibiotics that saw widespread use. They went out of favour because of resistance. Of course, the term is very broad, so is there another type of sulfonamide, or other sulfa drug, that you are referring to? 

Sulfonilamides are aniline derivatives - chemotherapeutics not antibiotics per se.  As hypervalent said, resistance is an issue both specific MRSA and general - pseudomonads and anaerobes.  Antibiotics when developed were more effective.

Wait, shouldn't it be sulfanilamides? But regardless, resistance against those compounds were also found decades ago, rather unsurprisingly.