EOS 350D - random smudges on pictures

Hi everybody,

I've been reading articles on DPReview for quite a while but never followed the forum yet so I hope my post is in the right place. Apologies if not and let me know where I should post it.

I have an EOS 350D since 2006 (I know that's not exactly a recent camera!) and which has been working fine ever since. I've used it in all my travels and in all types of conditions so it has seen and lived a lot already (and probably suffered a bit). I have 2 lenses I use with it: a rather old Tamron 28-75mm and a slightly more recent canon 10-22mm. Both lenses are associated with polarizers (at least in the conditions of the pictures I'm concerned about).

My problem is that I've noticed on a good number of pictures I've taken during a recent trip to Nepal some dark green smudges are appearing rather randomly. As you can see on the examples I've attached "noticed" is somewhat an understatement as it is pretty obvious and annoying. It doesn't seem to have always the same shape nor location so I don't think it is dirt on the CMOS. It also appears on pictures taken with both my lenses and it is there for various light conditions so I don't think that's anything similar to a flare. It's also not a problem of conversion to JPG as the RAW ones have the same.

Would you have an idea of where it comes from? Data corruption? Dying CMOS? (don't tell me that, I'd have to buy the 5D I've been tempted by for ages :)) Others?

And if you happen to have an idea of what the problem is, do you know how to solve it?

Thank you for your help anyway! Cheers.

Lense 10-22mm, low light, smudge on top (circular shape)

Lense 28-75mm, smudge on top left (in the cloud), no particular shape

Lense 10-22mm, smudge on top (in blue sky above the flare)