Red, hard, large bump on my wrist from my Apple Watch 7

Seeing a doctor seems like a good idea.

I haven't experienced this-- most people haven't--and I hope it goes away soon. I have heard that some do get skin reactions from wearing the watch. It could be from allergic reactions to nickel or other materials in the watch. Apple says this:

Another potential cause of discomfort is wearing your Apple Watch too tightly or loosely. An overly tight band can cause skin irritation. A band that’s too loose can cause rubbing. If you experience redness, swelling, itchiness, or any other irritation, you may want to consult your physician before you put your Apple Watch back on.

There's a bit more information here from Apple:

Wearing your Apple Watch - Apple Support

Thank you for participating in the Apple Support Communities.

We want to make sure you reach the right team for help with your device. We recommend that you contact Apple Support directly. Depending on your region, you might be able to contact them here: Get Support.

LoriDegre wrote:

I’m not sure what I should do? Contact Apple?

You should contact your doctor. Apple cannot give you medical advice.