Just wanted to share my encouraging story for those of you who are struggling with simliar problems in case my experience will help you.  In May, 2013, I experienced a sudden loss of the sense of tasting sweet.  My sense of smell was just fine.  I could taste bitter, sour, salty, savory (although most things tasted a bit "off" due to the sweet factor missing) but no sweet taste at all.  So many things tasted plain nasty, especially fruit.  I love chocolate...but the sweetest milk chocolate was like a spoonful of baking cocoa.  It was concerning and also made me very sad thinking of never tasting sweet again.

I had an onset of a migraine the same day as the loss of sweet taste.  I am still unsure as to whether that had any connection or not.

I waited a couple weeks to see if the taste would resolve on its own. When it did not, I went to my family doctor, who do many tests, none of which showed anything problematic or helped.  I then went to an ENT to did several tests and put me on a steriod.  Didn't help.  If anything, the taste issue got worse.  I also was having a lot of dry mouth issues at this point, which I had not had before.

Then went to a neurologist.  Had an MRI to rule out brain tumor, etc...  Everything was fine.  The next step the neurologist recommended was an infusion of a cocktail of drugs (similar to chemotherapy) to try to shock my body out of an "extended migraine state" which is what they believed might be happening...no one was sure. 

To clarify, my migraines have often had visual symptoms but not always the typical terrible headache.  They thought the taste loss might still be a result of the migraine.

I was reluctant to infuse bunches of drugs.  The steriod experience wasn't pleasant.  I hated the thought of my taste never being normal again, but also didn't want to do things to make my body even more out of whack. I decided to just give it more time and hope that it would resolve on its own.

In mid August, three months after my taste loss, I went to a chiropractor.  I ONLY went as I had a groupon about to expire for a free massage.  It included the "free consultation" with the chiro doctor, so I talked to him about the taste loss, not thinking he would have any advice, but more a "this is a weird thing that no one can help".  Dr. A told me he had two prior patients with taste loss and both of them had it restored after multiple chiro treatments.  I opted to let him "adjust" me, really not believing it would help at all.  I also had my free massage.  :)

After going home I didn't even think about the fact that my taste might have improved.  I really had no confidence Dr. A's treatment would do anything.  A couple hours later, I tasted something and realized it tasted different...better.  I quickly realized that my taste had dramatically improved.  After that first treatment, I would say it was 75% back to normal!!!  I continued treatments twice a week for several weeks and my sweet taste is 99% back to normal.

In the last year I had one other time that my mouth started to feel dry and taste was a little "off". A chiropratic adjustment ended up setting that right as well. 

I belive in my case the taste issue was a pinched nerve in my neck.  I had been having a lot of neck stiffness / some pain prior to the taste loss.  I'm not sure why only sweet was affected.  My family doctor is not so sure the chiro treatment did anything; he thinks it was a coincidence, but with the timing, especially given that I did not have any confidence it would even help, I have to believe that is what helped me. 

I also believe God led me, at that time, to that very chiropractor to help me out of the loss of sweet taste.  I don't know that every chiropractor has the experience this one had to help, but it is definitely worth trying. 

Hope that anyone reading this still having problems is helped as I was!  It is definitely no fun not tasting sweet.  Blessings!