Well, Dawn, you need to replace it! You could douce it with bleach, but if it's already loose you'll end up meeding to replace it.
Sorry
Salena

I have the same problem with black spots on clear calking! The only solution I have found so far is removing and replacing it!
Any other suggestions and help would be great!
Thanks.
Chantal

Caulking is usually only mildew 'resistant,' which means you'll need to clean it out and replace it. Treat area where you have removed the caulk with denatured alcohol and make sure it is dry before you replace with new caulk.

I have found this to be a positively hopeless endeavor. The good news is that the caulking is easy and inexpensive to remove and replace, and you will be happy to see a new product in the tub. Good luck!!

What is the type and brand name of the best caulking to replace the shower walls caulking?

I've used DAP Kwik Seal Tub and Tile Adhesive Caulking and been very pleased. It goes on very smooth and holds up well. I've yet to find one caulk that outlasts the others better in a shower area. My two cents and good luck!