mobile

As the title says, since I updated to 5.1 about 3 days ago after not using my nexus for about a month my nexus is now completely unable to register a signal with T-Mobile about 98% of the time. My phone is rooted, but other than that it is all stock, I have tried using the SIM on a different phone and it works perfectly only in my nexus does it not work. My APN is set to the correct one and all of it is set to the right values. When I try to manually select my network provider as everyone has told me to when I select T-Mobile it will bring up a box that says "registering to t mobile". After about 30 seconds a notification appears saying "Selected Network unavailable". Does anyone have any help they can offer, or is anyone else experiencing this or any similar problems? Please let me know. Thank you!