ok so i read pgs. 128 and 129 about injury and sickness and it said the thing about going to a healer… what if you have the healer skill? can you heal yourself? because in RL you would be able too, but what about in MG?
Yes, you can. Of course, you’d be down 2D due to your Injured and Sick Conditions, but you can absolutely use the skill on yourself.
For treating wounds I’d say you should get an extra -1D (which could be neutralized if you get help with a +1D) since it’s hard doing first aid on your self. On the other hand if you treat illness with medicine you shouldn’t have any minus for treating yourself.
There’s really no need for additional penalties.
Why’d you be down 2D?
I would say if you were a healer, and you were treating yourself, you’d go straight to the Ob 3 Health/Healer test. Additional help would give you +1D.
Page 124 and you will see why 
Ah yes, thanks! So it’s still an Ob 3 Healer test, but with -1D for Sick/Injured (or -2D for being both Sick AND Injured, ouch!), plus any additional die for teamwork and -wises.