I deeply apologize for the Sonny and Cher reference. From pics I was sure. Goes to show ya, you can't judge a book by, etc, etc...
I know who Sonny and Cher are (or were in Sonny's case), you old goat. Used to watch 'em on the Smothers Brothers (google it Tanner). I just love to call you an old goat.
My recommendation for what ails you has naught to do with the pack. How are you fixed for hip, hamstring, and lower back stretches? Especially the hip flexors? How about foam rollers and stretching for the IT band?
I've had similar problems in the past and it always comes down to being too tight in certain places. Especially for guys who do resistance training, that will tighten you up.
Find a good DPT, and have her put you on the table and see where you're tight. Chances are, even if you stretch 90% of what you need to stretch religiously, you're missing 10% somewhere and she'll find it.
put you on the table and see where you're tight. Chances are, even if you stretch 90% of what you need to stretch religiously, you're missing 10% somewhere and she'll find it. 
