In Thy Flesh?

Can anyone tell me more about this WAD? Was it an offical WAD? Where can I obtain it?

I own Ultimate Doom 95 and Final Doom.

You're not by any chance referring to "Thy Flesh Consumed", are you? Because if you are, it is the 4th episode in Ultimate Doom. Other than this one, I believe that Final DooM, and Master levels are the only "official" id Software add-on releases in the DooM series. Thy Flesh Consumed was free, but the others were sold commercially.

In Thy Flesh may have been an add-on, but was not an official release. Check ftp.cdrom.com for add-on levels. If I can locate the wad for you I'll post here.