new Float: pHealth[MAX_PLAYERS];

SetTimer("CheckH", 1000, 1);

stock SetPlayerHealthEx(playerid, Float: health)
{
    pHealth[playerid] = health;
    SetPlayerHeatlh(playerid, health);
    return 1;
}

stock GetPlayerHealthEx(playerid, &Float: health)
{
    GetPlayerHealth(playerid, health);
    return 1;
}

forward CheckH();
public CheckH()
{
    static Float:old_health;
    foreach(Player, i)
    {
        GetPlayerHealth(i, old_health);
        if(old_health != pHealth[i])
        {
            SetPlayerHealthEx(i, pHealth[i]);
        }
    }
    return 1;
}

new
    Float:g_afPreviousHealth[ MAX_PLAYERS ], // This variable holds the last known health of each player
     bool:g_abIsSpawned[ MAX_PLAYERS char ]  // This variable defines wether a player is spawned or not
;

public OnPlayerConnect( playerid )
{
    g_abIsSpawned[ playerid ] = false; // The player just connected - not spawned
}

public OnPlayerStateChange( playerid, newstate, oldstate )
{
    if ( newstate == PLAYER_STATE_ONFOOT || newstate == PLAYER_STATE_DRIVER || newstate == PLAYER_STATE_PASSENGER || newstate == PLAYER_STATE_SPAWNED )
    { // ^ If the new state is one of the states spawned players has ..
        if ( oldstate == PLAYER_STATE_NONE || oldstate == PLAYER_STATE_SPECTATING || oldstate == PLAYER_STATE_WASTED )
        { // ^ If the old state isn't one of the states spawned players has ..
            g_abIsSpawned     [ playerid ] = true;  // The player is now considered spawned
            g_afPreviousHealth[ playerid ] = 100.0; // Health is set to 100 when you spawn
        }
    }
    else
    { // The new state is one that spawned players don't have
        g_abIsSpawned[ playerid ] = false;
    }
}

public OnPlayerUpdate( playerid )
{
    static
        Float:s_fHealth
    ;
    
    GetPlayerHealth( playerid, s_fHealth ); // Get the current health
    
    if ( s_fHealth != g_afPreviousHealth[ playerid ] ) // Compare it to the last known health
    {
        if ( s_fHealth > g_afPreviousHealth[ playerid ] )
        { // The new health is more than the previous!
            static
                s_szMessage[ 64 ]
            ;
            
            format( s_szMessage, sizeof( s_szMessage ), "Health increased for player %d: %0.f -> %0.f", playerid, g_afPreviousHealth[ playerid ], s_fHealth );
            
            SendClientMessageToAll( -1, s_szMessage );
        }
        
        g_afPreviousHealth[ playerid ] = s_fHealth; // Set the previous health to the new one
    }
    
    return 1; // Never forget this in OnPlayerUpdate
}

else if(old_health < pHealth[i])
{
     pHealth[i] = old_health;
}