Sick cactus

Does anyone know what I can do about this cactus. It is quite yellow and I don't know what to do with it.
I've repotted it but is there anything else I can do ... ?

 

Tricky, has it a some time had root rot?
How long is it since it last showed signs of new growth?

 

Hi @pete I don't think it's had root rot. Last time I saw it, it was all right.
I haven't watered my cacti for a few weeks because of various reasons. Maybe that's the reason, but I thought cacti were drought resistant.
Last year it had a beautiful mauve flower.

 

Do you know the species @Michael Hewett ?

Is the plant body slightly soft?

 

Thanks @pete

It's called Acanthocalycium violaceum - beautiful violet colored flower comes on it.

I don't think it's soft. It's too spiny to feel properly but I don't think it is.

 

Check it up on the web.
Possibly too much sun, or not enough, maybe the repot will sort it out, but there is not long left now for any improvement this year.

 

I`d repot it with a very gritty soil. Give it a light feed with cactus food. Make sure its got plenty light but not fry it on a window sill allday.
Go easy on the watering but I like to give mine a good drink in summer then let it dry before it gets another watering.

 

I only have 2 cacti, they just live with no attention from me, as I know nothing about cacti, south/east facing kitchen window cill all winter, then after last frosts go outside, same aspect, never ever water, they get rained on all through our great British summer, then bring in as weather cools.
Trying to upload a photo, come back to it.

 

Thank you all for your advice
Thhe cactus has has shade most of the summer, and very little water. I've repotted it now and we'll see how it goes

@pamsdish your cacti look like Euphorbia horrida (left, and not a true cactus but a succulent Euphorbia) and Ferocactus latispinus (right - a cactus from Southern Mexico)

 

you are probably correct @Michael Hewett it seems to have grown another couple of inches this year.