Regarding Hotspot and Bluetooth

I`ll explain my whole situation from the beginning.

I purchased an IPad mini 4 (wifi only) recently, Now I have an iPhone 6 as well with unlimited internet, and hotspot enabled with my carrier.

Now my first issue was while I enabled my hotspot so my iPad mini can connect to it, I noticed the connectivity was poor, constant lag, and when I would receive a text or call it would disconnect my iPad from the wifi. I would have to reconnect constantly, you can see how this became extremely annoying and aggravated me.

After doing some research on the forums I read somewhere that when I enable the hotspot first I should disable bluetooth, and when I enable hotspot a pop-up appears basically asking me to reenable bluetooth, or hotspot can only be accessible from "WIFI & USB ONLY" after more research I realized I would have to select the "WIFI & USB ONLY" settings. Once I disabled bluetooth, turned on hotspot, and pressed the setting for WIFI & USB ONLY my situation was solved. I got and still get a very reliable connection, able to watch movies on long drives while receiving calls and not losing connections, able to FaceTime, and more.

I haven't had a single issue since I found this out; although, I now have a new problem!!!! once I am done using my iPad, I try to restore my iPhone 6 to its original settings, "hotspot off" to save battery and reenable bluetooth on my phone, now this is the issue, the little switch under bluetooth settings both on the drag up menu, and from settings I try to enable bluetooth it turns on for a second, then instantly goes back off, no matter what I do I can't find a way to fix this issue in the settings, nor online. Only solution I have found so far is pretty lame, its restarting the phone entirely. Now I am starting to get curious, when I select "WIFI & USB only" does that some how disable bluetooth in a deeper setting then I can see? Any help would be much appreciated I tried to explain the situation to the best of my abilities with the most details as possible, if you need any more information to possibly help me out please let me know.