Hi there,
If they are making you that drowsy, then by all means, take them at night...that way you should get a good nights sleep...with, hopefully very little hangover in the morning. But, if you are very hung over, then perhaps these pills are not for you...that can happen...and you will hve to go back to the doctor and talk about it.
I take Celebrex 200mg twice a day...and it has really helped my back...which is permanently injured...I still get some spasm...some days worse than others, but I use heat...pressure etc...to get relief from that.
I am worried about the Tylenol 3's with this diet...constipation can be a big problem, and codeine is very constipating...so if you are taking them, remember to eat some fiber, and drink lots of water.
Hope that your back feels better soon...but don't try to drive when you are that whoozy...