Pulmonary Embolism Support Group
By far the most common form of pulmonary embolism is a thromboembolism, which occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. Symptoms may include difficulty breathing, pain during breathing, and more rarely circulatory instability and death.
Unfortunately, there isn't a magic formula for working out if you need to go back to A&E, apart from to say it is unlikely that you're having new clots, if your especially if INR rate isn't too out of range. After 4 weeks, your SOB, fatigue, leg pains will fluctuate and may do so for another few months. As you say, this probably isn't anxiety related, your body is simply doing its best to recover from something serious.
Generally, the biggest risk of getting new clots (while on warfarin) is if your INR is significantly outside the range, for a reasonable period of time. If your INR drops a bit (while still in range) or even dips to 1.9 or 1.8 for a few days it won't be significant (you're probably getting monitored weekly or twice a week). Sometimes, it is easy to get too focused on the INR number, simply because it is the only objective measure of treatment we get during this time. As long as it is about right, your body will probably be recovering.
What to do? If there is a significant problem, you should get it checked out. If it is similar to what has gone on before, give it a good few days. If things get noticeably worse over that period, think about getting them checked out. Not sure if I can tell you what I mean by significant or noticeably though :-)
SOB can be really hard to understand for a while. For me, it took a few months to start to see a clear cause and effect. I pushed myself too hard for a few days ... more SOB. I went for a walk in super-humid weather in Texas in the summer ... more SOB. I went for a walk in sub-zero weather in Colorado in the winter ... more SOB. I had my carpets cleaned and there were a lot of fumes ... more SOB. I'm fighting a cold ... more SOB. A lot of times when the SOB increased, I could usually find a cause OR it would go away after I gave myself some time to rest.
I mean, I did a couple repeat trips to the ER myself for increased SOB and it usually wound up being anxiety. A few of those, and I felt like I could try to get a handle on the anxiety ... and that would help the SOB. I will say also that anxiety is a sneaky thing. It can disguise itself as any of a number of symptoms. And maybe you don't actually FEEL anxious, but that doesn't mean your body is acting like you are anyway. Very hard to work with.
I know my allergy doc gave me a simple exercise to do after the PEs. He said, sometimes we get so caught up in the new, stressful way of breathing, that we forget how to breath normally again and we need to remind our bodies. Once an hour, on the hour, he wanted me to take a deep breath, hold for three seconds, let it out, hold for three second. Repeat twice. (No more than that, or you'll wind up hyperventilating.)
I only did the exercise for a couple days, but found that it calmed me right down and made me feel like I had some control over the situation.
For me, I always ask, "Would I have gone to the ER with this BEFORE the clots?" If the answer is no, I don't go.
Also, if your INR is above 2.0 and staying about 2.0, you don't need to do much more. You'll never get "stable" enough that you're at exactly the same number. It practically never happens. I've been swinging around between 2.0 and 3.0 for months now, rarely the same number twice in a row. But that's in range, so no one is worried about it.
Hang in there!