Increasing Methotrexate causing problems?

I have been taking Methotrexate for 6 months. i started with 15 mg, bumped to 20 mg and things seemed to be improving, but still active so I was bumped to 25 mg. The very nexy day after taking the new dose i started becoming symptomatic with very stiff joints and throbbing pain. It subsides a little as the week continues, but once I dose again the pain is back. Is this normal and will my body eventually adjust and the activity subside, or is this my body saying this med isn't working?

It is unusual for patients to flare after the weekly dose of MTX or with increasing the dose.