For some reason I can no longer taste anything sweet.

See your doctor. Nothing can be done online... smell has a MAJOR factor in the sense of taste. Tests can be run and causes eliminated or confirmed in the office.

But I can smell just fine.

Even smell is not always an all or nothing proposition... like hearing (I've had temporary and sudden loss of a certain frequency range, as in, it was there when I went to bed, but not when I woke up, that later returned weeks later after treatment as an example). Certain facets might have been affected. While others not.

Still, the only way to get to the bottom of this is a clinical exam and tests.

Taste can have a lot to do with wellness. When ill taste can be offset, be different than normal. It could be a simple cold, or flu, or it could be anything between all the way to something more serious.

The only way to find out why this is happening, is to see your doctor. Be prepared for numerous questions and tests.

Sadly this cannot be diagnosed online, not even by a doctor. It's simply not possible.

Good luck.