[Pruppet]

bool g_bIsPlayerDamaged[MAXPLAYERS + 1];

if (GetClientHealth(client) < GetEntProp(client, Prop_Data, "m_iMaxHealth"))
{
	g_bIsPlayerDamaged[client] = true;
	
	// Do code.
}

if (g_bIsPlayerDamaged[client])
{
	// Do code.
}

Untested, but should work