Can soaking in bath water cure/help anxiety/lower back problems? Anything I should do?

If you like. Many people like a nice hot bath, with some aromatherapy in it as well. There are bath salts that have lavender -- very relaxing. Massage can help back pain also. If it persists, you should see your primary care doctor for an eval for back and anxiety. S/he may want to get xrays or MRI to make sure all is well anatomically. Physical therapy may be an additional help for back.
MANAGE?!? I do not know about "cure" but it can certainly help and probably not harm. Remember that very few illnesses are truly and absolutely cred. Most are managed so that you can pursue an active and productive life.