[Tiara Open] 38 open 2006 smell in cabin

[MC1600]

If you have a holding tank, you have a holding tank vent. Looks like this:

https://images.app.goo.gl/yx2crxU2k2TwnDBW9

Another source of rotten egg smell can be your freshwater system, though that wouldn’t tend to linger for a week.

[ReelMagic]

Agree, all waste tanks have vents but not all have vent filters. I was told my boat came with one but have been unable to find it...

[Sapphire]

So we still have the smell and did everything you all recommend as for the filter for the toilet we looked everywhere for it for two years now and no where to be found we decided to take out the take out the tank the summer and put a new one in..hopefully that will help with the smell

Sanitation hoses can also become permeated and need replacement.  But rotten egg smell is usually battery related as pointed out in earlier posts. 
To see if a hose is permeated, take a clean rag, saturate it with warm water, wring it out a bit and wrap it around a hose.  After a few minutes take the rag off and sniff.  you will know if that is the source....