Monodevelop "name does not exist in current context" prolem everywhere (Linux)

I'm having a big problem, when trying to edit scripts in Monodevelop, I get countless red highlighted text around things, saying they do not exist in the current context (including monobehavior).

The scripts do function when saved, but this problem makes it essentially impossible to make the scripts to begin with since I can't autocomplete anything whatsoever or see if I typed things right.

I'll point out/note that I do not have any "Monodevelop" folder anywhere inside my Unity editor folder unlike what every other solution I can find anywhere indicates, my path goes

 /home/myname/Unity-2018.1.0b8/

And from there on out nothing called Monodevelop exists, no "opt" or anything, I got the Unity editor to recognise Monodevelop and open scripts in it by going to the path:

 /usr/lib/monodevelop/bin/monodevelop.exe

I have a sneaking suspicion that this is something to do with the fact I already had Monodevelop installed before getting Unity, but I have no idea how to fix this.