You said "He isn't one to talk about it much and it's a subject we avoid at all costs "
Why though? I can understand that you are a private person/couple, but you really ought to be able to talk about intimacy, including sex with your sexual partner. If you have embarrassment issues about talking about sex, its no wonder its difficult to resolve problems in that area.
I'm sorry to hear about your DH's medical problems, if he is experiencing loss of libedo as a side effect of his medication then he really should go back to his GP and see if there is anything they can do.
As for the lack of intimacy and physical affection, I think you need to explain to him how important that kisses and touching is to you and that you don't expect it to always lead to sex.
I realise that in the past sex maybe just happened without the need to discuss it but in a situation like this you really need to talk to each other so you can say "I don't feel like sex right now, but I would love a cuddle" or "I understand if you don't want to take things any further but I miss you holding me". Basically you need to get back to a place where you can enjoy each other physically without the expectation that it will lead to sex (because at the moment sex isn't appealing to him and I'd imagine the rejection is hurtful to you) oddly enough this might take the pressure off and make sex a possibility.
In the longer term, I guess you need to know if there's a solution to the effect of the medication, he needs to ask his gp.