My cat’s back is twitching and he’s running around

With the full disclaimer that I'm not a vet, it sounds likely that your cat has hyperesthesia. Hyperesthesia is a disorder that seems to be relatively common in cats. Its symptoms include things like rippling/twitching skin on the back, frantic licking, running around frantically, and thumping the back legs. It often gives the general impression that the cat has a sudden itch or like a bee suddenly stung it.

Generally unless it's particularly concerning (sometimes the cats will self-mutilate as a response for example), the treatment is mostly preventative. Hyperesthesia is exacerbated by stress, for example, so you attempt to prevent episodes by keeping your cat as stress-free as possible. Or, as is the case with my cat, there's an obvious trigger (for some reason my cat is triggered by the smells of cooking), and you can try to keep that trigger to a minimum. Cat-nip might also help alleviate symptoms as it's a natural minor sedative. But if the symptoms are more concerning, then there are drugs that can be prescribed by your vet that might help.

At any rate, it's probably best to consult with your vet to verify it's indeed hyperesthesia. Take video of your cat during an episode if you can and show it to your vet, as that can help with the diagnosis.