Hi Maria,
I was suprised to hear you say that you had not received a response to date, as new posts that are not answered usually stay a top of postings? Sorry from everyone for this.

I cannot be sure Maria from the photo, but the white speckling on leaves could be from spider mites.
I would treat for mites at intervals of 5-7 days for 3 treatments. Make sure if you spray the leaves with a contact insecticide, that it is not done in sun. The leaves could burn.
If concerned about burning and you use a contact insecticide, then you can rinse off with water after an hour or two. I do not use systemic, so I cannot give advice.
Not sure about treating for both at same time. Have to be clear as to what issues you are dealing with first.
I fertilize mine when in full growth every time with 1/2 strength and this is watering once weekly. If more then I water in between with plain water.
It is recommend if you can fertilize with something similar to 9-3-6, or 24-8-16
I hope that this helps you.
Rick

Thanks Rick
I have been overdoing it a bit by the sounds of it. You have given me a good routine I can follow and will look forward to any further advice that you can give me.
Thanks so much Maria

Maria,

It looks like mine plants dealing with bad mite infestation. I don't know about any systemic to treat it, so I spray, multiple times and hope for the best! Make sure you spray both sides of leaves, and do it every week for at least 3 times. I get it every winter, they like dry weather! Number of times I got desperate, defoliated and sprayed stems and caudex. Water helps, if you can give your DR shower!

Aggie