Feeling awful

I'm agoraphobic, but following CBT I have been doing really well. I have got to places I haven't been in years, both by myself and taking my children (6 and 1).

However, in the last couple of days I have been getting an unpleasant 'cold sweat' feeling on my back. I ignored it and it seemed to go away by lunchtime.

I took my son to school today. Had the same feeling, was also feeling anxious but this is something I feel pretty much every day. I just have to work through it.
I went to the shop, then decided to go for a walk round the block as it is too hot for me to venture too far out and I was finding it hard to shake the anxious feeling.

I was going round for a second time (CBT goal is to be out for at least half an hour) when I suddenly felt really out of it, my ears felt blocked, it felt like I had a hat on (!) a cold sweat feeling went through my entire body and I felt really faint. I didn't faint (never have, but is a fear fr me) but I felt like I disappeared for a split second. I know that sounds weird, but I can't think of another way to say it. I turned round and walked home, feeling awful-although I met someone I know who said hello to me and I cheerfully answered while feeling like I could keel over. I was shaking and my skin felt prickly like the nerves were all on edge.

I haven't stopped crying since and have a bit of a headache and feel generally a bit 'out of it'. I was doing so well and this has scared me so much. I feel like my body can't be trusted and I don't want to go out again.

It feels like 1 step forward and 20 back.