Can my tsh level of 4.22 cause me to be spotting with brown discharge 2 and a half weeks before my period is due?

Unlikely: The TSH level is not the true evaluation of hypothyroid. But true hypthyroidism may cause some interference with horkames especially if the abnormal thyroid studioes indicate a pituitary problem but just the TSH of 4.22 would not be enough to worry about without knowing the freet4.

Possibly, yes: I would recommend a full thyroid panel and vaginal ultrasound first. If all else is normal, it may help to start a very low dose thyroid medication.