Might Have Warped Rear Corner of Hood

[dsraven]

a pic would really help but if there is room behind the weld you could smooth it out with a flap disc and then try the hammer on dolly routine. that will stretch the metal that has shrunk from welding. usually the welding will cause a shrinkage so it should be done in small spot welds and then planished while still hot, right after the weld is done, to help eliminate the stresses caused in the metal from the heat put into the metal while welding. there is a good little book that can explain a bunch of practical techniques to remove dents and weld panels, it's called "the key to metal bumping". at first glance it looks like a really old school book but the principles never changed so it is still relevant.
anyway, getting back to your problem, post a pic if you can, from both sides of the panel if possible, and maybe we can help you figure out what to do next. an explanation of how you welded the holes would also help possibly. did you use a backer panel on the rear, a heat sink copper plate backer, something else back there, did you simply weld around the outside of the hole like filling a donut hole in one step?