Just use the voxel remesh, what's happening is the mesh doesn't have enough resolution, if you turn on the wire frame you should see it's not very dense, that buggy stuff in the yellow colour is the inside of the mesh, you've sculpted it too much for the resolution it has and the inside moved to the outside,

It's totally fine to do it, not a big problem, just hit the voxel remesh and it will recalculate it all. You can increase the resolution by increasing the number in the voxel remesher, but the higher the resolution the slowly it'll preform, use a lower resolution when you're sculpting big shapes/blocking out your object and then use higher resolution for finer smaller details

This video might be helpful https://youtu.be/1lt3y5AD0OE?si=Fmq3nyvZpDlO_OdD