There is nothing important in the house of madness, but if you want you could try deleting all of the files in the '..\Divine Divinity\Run\Dynamic' folder, then save and re-enter. The halberd from the cursed Abbey drains stamina even when it is just in your inventory, so shouldn't be the cause this stamina drop. You should not have had any problems picking up items, assuming you were not encumbered and were standing close enough.
The dynamic folder is used as a cache for the game. Files are created / copied there from the save game folder when you load, and written / copied from that folder when you save a game. The files will be re-created as required the next time you start Divinity. If there was a corrupt file in that folder, deleting the files should fix the problem.
