90 day global means that your insurance paid a flat rate for your surgery and follow up appointments for the 90 days since your procedure. All care at your surgeon should be covered during that period. Perhaps others in the same specialty can't get paid during that time? I am not sure.
definitely try getting in the pool. It will be easier than walking and will get you some much needed gentle movement for that limb.
This is absolutely a big deal. It is hard for others to understand and they are often frustrated, scared and potentially not coping great either. Don't feel like a woosie. Surgery of any kind without complications is stressful and anxiety producing. Why the heck wouldn't you be having a hard time? Having your mobility taken even temporarily is enough to put most people into overdrive. It is hard in the beginning. Be kind to yourself, knowing that you are doing the best you can right now.