In answer to tight hamstrings...yes... They can cause many problems with the body. Women are always being chastised by doctors for wearing high heels which can cause any number of problems for the feet, but also the back as well, even the shoulders. Think of the old song.."the foot bones connected to the ankle bone and the ankle bone's connect to the shin bone......." It works the same way with the muscles. They're all connected to each other.

So when your major muscles get tight, even just one set, it puts strain on everything. It's a little less noticeable and causes a few less problems if it's a tight bicep. You might notice some grip involvement or tightness in the shoulder more than anything else, but then the arm has more resting time than the legs.

So the hamstrings get tight and get no real rest, but more than that too, when the hamstrings are too tight they change your posture to. Your weight is carried more forward on you feet and as counterbalance your lower back is thrown backwards to stop you from tumbling head over heels. It's not consciously done, your body will wiggle which ever way it needs to to stay upright.

The same this is happening with the neck involvement. Because you want to look ahead and not down at your toes (as you would be with your lower back pushed out to avoid tipping over on your toes that your hamstrings are making you walk on) your needing to bend it backwards to see where you're going. These aren't exaggerated shifts, and don't need to be either to cause massive amounts of strain upon the muscles and the joints.

Keep up the PT get those hamstrings stretched out, be mindful of your posture and you should start to feel relief. And since it's not MS apply plenty of warm moist heat to relax those poor muscles. Be it in a nice bath or hot shower or just curled up with a heating pad. But most importantly listen to the body, don't wait till you're ready to pass out or dizzy to take a rest and give the muscles a break.