Have name-changed due to TMI-ness. 
Right, on Sunday night, I had some serious itchiness going on around my back passage and my first thought was 'oh crap! Threadworms!'
But I've checked (believe me, mirrors, torches, all sorts) and there's nowt to be seen. The itchiness has carried on but it's not only at night time. I don't know what else could be going on!
Please help, wise Mumsnetters! 