Yes, you still can clot.You should have a Doppler Ultrasound once a year (min).
INR changes due to whar you eat and the medicines you take. Do not eat or take Vtamin K it will alter your INRS. Plus, supplements and some medicines will to.
It does need to be monitored every month.
I wish someone would have replied sooner so I hope you receive this.
Your pain might be a secondary condition and one should have a thorough check up it is hard to guess as I found my clot caused extreme pain and I had a PE. Which I almost did not live to post here today. It should never be taken lightly.