Hey, I experience the same things on occasion, i would become so self aware of my surroundings & self conscious that when i walked my legs would be all stiff & robotic & i would begin to count each footstep which was annoying! I also sometimes feel that my face is frozen & feels tight like all of my muscles are ceasing up i & would think that people must be thinking i'm really weird for my awkward posture & nervous facial expression etc..
I don't really have any tips as i still sometimes suffer with it, but what i try to do is distract my mind the best i can, so if i walk into a store i try & think of what shopping i need, or anything else i can think of to take my mind on how nervous i feel, also what i do is i refuse to let the nervousness get the better of me, if i walk as stiff as a robot or if im dying of fear i refuse to let it get the better of me & subconsciously my anxiety is beginning to learn that i wont let it win, so when i walk into a store now & my legs go stiff & i act nervous etc.. i say to myself " don't worry this will soon pass just let the anxiety peak for a short while then it will decrease, Then after a few mins of self relaxation talk i tend to loosen up & my legs become relaxed & i can feel my facial expressions coming back into my face.
All i can suggest is no matter how bad it gets, tell the anxiety that you are not going anywhere & that you are in control no matter how awkward you feel or look you just have to stay in that situation long enough until your body & mind learns to relax, then after a while it will get easier. I used to suffer badly with this, but now when i get the symptoms i know they will subside after a short while & it is gradually getting better overtime, good luck