Ice massage 2 hourly or as often as possible, optionally plus immersion in a bucket of iced water
Eccentric stretches (see link above to Alfredson protocol), but be a bit careful to make sure you have the strength to do them. Better to build up slowly rather than make it worse. Note, the original study added a weight load over time as well, but was based on runners who started with strong calves.
Be careful if the tendinopathy is at the insertion into the heel - the stretches could be damaging.
I'd avoid ibuprofen as there is some limited and inconclusive evidence that it can weaken the healing tendon, plus it's not an inflammation in any case.
See a physio if it does heal reasonably quickly, but it will likely take months not days. I did the stretching a couple of years ago and no longer have callouses on my Achilles and no pain, so it can work.
Mike (aged 51)