Okay, so Ashurity, I looked up the scientific facts about how Methotrexate works... And this is what I came up with....
This medicine acts by altering the body's use of folic acid (a vitamin), which is needed for cell growth. Scientists suspect that this interference with folic acid is an important reason for methotrexate's benefit in rheumatoid arthritis. Methotrexate belongs to a group of medicines that are called "second-line therapies" or "disease-modifying anti rheumatic drugs." These drugs may affect the activity of RA to a greater extent than commonly prescribed drugs, such as aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs). Methotrexate is usually taken along with NSAIDs. It may begin to work as early as three to six weeks after beginning treatment.
so while she is taking this it is important for her to also be taking a multi-vitamin because this drug uses her Folic acid intake to the max to help with the growing back of her good cells.
Lucy has an Auto-immune deficiency which as causing her immune system to overcompensate and is attacking her joints.