Ah I understand as my DSis also injects methotrexate too. It's a real struggle. I've no idea really but I would try a no silicone shampoo or the gentlest shampoo you can find (baby shampoo?) to try and stop the hair trying to replenish the oil. And when dry, spraying a dry shampoo into the roots. Try a simple haircut so you don't have to touch your hair as much. Worth a go, no idea if it will help, sorry.