Enfilade, Carbonfiberboy, thanks again for your input. It seems the injury wasn't as bad as I'd feared. I think personally that after hurting it before, I knew what it felt like when the tendon just started getting unhappy and acted fast enough to prevent it becoming a real pain to try and get rid of.
Been taking the anti-inflammatory drugs religiously and I did NOTHING even remotely strenuous for a full week, not even walked if I could help it. I went for a sedate and easy ride of only 26km on Sunday morning (yesterday) and was sure to ride at a snail's pace for a full km before putting the speed up a little so as to warm up. No pain or discomfort, so I'm going to go for an equally easy run tomorrow (but with thorough warm-up exercises beforehand) and see how things go.
Thought I'd let you know, thanks again for the advice. Enfilade, I'm thinking of you through your recovery and just feel lucky that so far it looks as if I'm not as badly affected as you are. I'll probably also go to a local acupuncturist whom I trust for a few treatments, just to back up the meds and rest.
Good luck with your recovery, and hope you're back on the bike soon.