I haven't pooped in 4 days and have a massive blockage right at my anus. It will not move, help?!!!

Have you tried a glycerol suppository? Also when you've had the urge have you tried doing it in a squatting position? 

Do you take painkillers? 

If you need a fairly natural quick solution i would try a large glass of prune juice or two. sometimes fibre can have the opposite affect and bloke you up, Prune juice is a soluble fibre, always works for me. 

Take a natural laxative, one with sennosides 8.6mg.  Whatever brand name is available at the drugstore or supermarket.  In the US, it's Senna-Time, Senna-Lax, etc.  Drink lots of water with it.  Over the long run you must get control of the constipation.  Constipation is serious, and can lead to hemorrhoids, which are like torture. I've found most doctors to be unhelpful on both constipation and hemorrhoids.  I'm now taking magnesium supplements, 500mg to 1000mg per day, and this has helped enormously with daily regularity.  I've been constipated my whole life.

Try maybe two 8mg Glycerin suppositories and they usually do the trick providing the impaction hasn't been there too long, or an enema but I find they are too powerful and for me these days they don't seem to work for me. But suppositories do.