The OP's coin is money! I got this one a short while back among a random lot of four coins on eBay. Crispina Augusta, AD 178-182. Æ Sestertius Rome mint, struck under Commodus. Obv. Draped bust right. Rev. Salus seated left, holding patera, feeding serpent rising from altar, resting elbow on back on chair. RIC III 672b (R) The other three coins in the lot -- A Follis of Galeria Valeria, a Ptolemy VI Zeus/Eagle(Lotus series) Obol, and what I believe to be Heraclius 40 Nummi (w/ Heraclius Constantine & Martina). I'd like to think I did OK @ $65 for the entire lot.
My one Crispina: Crispina (wife of Commodus) AR Denarius 180-182 AD. Obv. Draped bust right, CRISPINA AVGVSTA/ Rev. Juno standing facing, veiled, head left, patera in right hand, long scepter in left hand, peacock at feet on left, IVNO. RIC III 283, RSC II 21, Sear RCV II 6001. 18.3 mm., 3.254 g. She certainly fits the long-necked paradigm. I suppose her hair falls into category # 2 of those listed by @Julius Germanicus, although I'd hardly call the chignon at the back of her head "simple." This looks like it must be the same type as the one just posted by @dougsmit , despite the very different obverse die.
Thank you for bringing it back and thank you all for showing more of your Crispinas! David Sear had the OP coin in hand and noted no tooling or smoothing on the reverse or elsewhere, but he emphasized the attractive portrait and nice glossy patina in his certificate . He describes the hairstyle as "elaborately waved in curls across head and fastened in a chignon behind". Also, "This attractive orichalcum sestertius features a sensitive portrait of the teenage empress combined with a seated figure of Salus, goddess of health. Although a standard reverse type, the appearance of the goddess at this time may relate to an imperial pregnancy." I really do like his detailed certificates for the interesting extra info they include that one does not get with his competitors.