Dots (rust?) on some leaves, need a solution [pics]

Here are the pics of my himalaya gold, its growing outside and has just started to flower. Some lower leafs have these brown dots on them, some have just a few of them, others are completely burned, as you see on one picutre. After looking around i found out that this is probably from pottasium defficiency, but i think i gave it enough nutes (maybe too much), so this must be a pH problem, resulting in a lock-up of nutes.

My question is this- is this really a pH problem, in which way do the nutes tip the pH scale (does the soil become more acidic or basic) and how to solve the problem, prefferably without commercial pH uppers and downers. (in short, would throwing some ashes around the plant help...)

Thanks for any help.

give them what they need something that has all the works

Hm, by giving them more nutes i will just tip the pH off balance more and make it worse, if the pH is the problem (which im about 80% sure it is.)

Hm, because the soil where im growing is pretty acidic (well at least around the hole, because i filled what i dug out with bought soil), and the sinthetic fertilisers i've been adding to them contain alot of phosporus, i think the soil is too acidic now and thats whats causing the problem.

I think adding some alkaline stuff like detergent should help, i must find something that wont kill the plant in the process lol