WiFi keeps turning off and won't turn back on

[wellsws]

Recently my MacBook Pro (15-inch, Late 2011, running OS X 10.10.3) has had WiFi issues. Most times after starting up, the WiFi will be on and my home network selected. Internet works fine. But then, usually after about 5-10 minutes, the WiFi turns off and will not turn back on until I restart the laptop. Then it does it all over again. Sometimes when it restarts the WiFi will already be off and sometimes it says there's no WiFi installed. I tried re-installing the OS but that didn't seem to solve the problem. Research I've done has pointed to something in the current OS? I tried deleting the WiFi settings and start over. Didn't work. I've noticed under the network names, the first item says "Wi-Fi: Looking for Networks" Then it switches and says: "Wi-Fi On". Under that it says "Turn Wi-Fi Off". I don't recall it toggling between those two items. Any ideas? I recently had the motherboard replaced at the Apple Store but this issue didn't start happening until about 2 months after getting it fixed (2 weeks ago). Any help would be greatly appreciated. This has been super frustrating.