Raspberry Cough Syrup

Anybody have this problem with Raspberry wine. I made this last summer
(2011). It is the most beautiful looking wine you would ever want to see! It just has a bitter taste. My wife describes it as robitussin or medicine tasting. More of a bitterness than tartness. It tastes really good with 7-up, but it is kind of hard to drink by itself. This was made with fresh raspberries from our garden. A Jack Keller recipe - about 20 lbs of fruit for 5 gallons. I didn't do any TA or PH testing. Could that be the problem? Or should it be back-sweetend? But like I say, it's sort of a medicinal taste.
Thanks.

Raspberries are acidic. What you describe can be classic for raspberries...all in the phenolics. Some cultivars are known to even lend a mint taste. You can definitely backsweeten, this will help balance the acidity to some extent.

I am curious will calcium carbonate help?

Maybe I could have added calcium carbonate earlier. It is too late for me this time. It has been bottled quite a while.