How long does the 4 month crash last?

Sorry to say this but I'm having a bad day today, I hope is because of the 4th month crash and not some other disease. I'm having this waves of like tremors that come and go, my left side has being feeling weak, clumsy and different form my right side, muscle twitching that went away for some days but came back again, mild muscle cramps. I'm really scare that this could be something else like ALS. I try to tell my self that is just the effects from Mirena, but when I feel ill I get really scare. I'm suppose to get my period on the 25th. Does any one know how long are these symptoms suppose to last if is the 4th month crash? Thanks I will appreciate your comments.