I put honey on top of mine and that helped, but here’s some stuff I found:

You can’t cure a cold sore, but you can alleviate the pain it causes by avoiding spicy or acidic foods, applying ice, and using over-the-counter remedies. Look for medicines that contain numbing agents such as phenol and emollients to reduce cracking and soften scabs. Abreva is an over-the-counter topical remedy used to help speed healing and minimize pain from a cold sore.

If your cold sore is especially painful or irritating, your doctor may prescribe an anesthetic gel to alleviate pain or an antiviral oral medication to speed healing or prevent recurrence. The antiviral agents available for treatment include acyclovir, famciclovir, and valcyclovir. These oral medications are more effective in treatment when started within the first 48 hours of the outbreak.

Cold sores can become complicated by a bacterial infection, so it is also important to keep them clean by washing gently with soap and water as needed.

This is probably more like a fever blister or a canker sore if it is on the inside of your mouth.Cold sores usually appear on the outside of your mouth like on your lips. I’ve used Abreva for my cold sores, and they cut down the time you have them significantly. Not sure if you can use it on canker sores. You may want to try Campho-phenique. It will burn a little, but it will get rid of it fairly fast, and is safe to use inside the mouth.