What are the requirements for plaintiff to state a claim under the Eighth Amendment for denial of medical care in his fourth amended complaint?

Generally speaking, plaintiff complains about his conviction, sentence and medical care in his fourth amended complaint. As with his original and first amended complaints, the allegations are too vague to state a claim upon which relief might be granted under the Eighth Amendment for denial of medical care despite the fact that in the court's previous two screening orders, plaintiff was instructed as to the requirements for stating a claim. As for his conviction and sentence, when a state prisoner challenges the legality of his custody and the relief he seeks is the determination of his entitlement to an earlier or immediate release, his sole federal remedy is a writ of habeas corpus. Preiser v. Rodriguez, 411 U.S. 475, 500 (1973).